New Strain of Covid – Cicada & NB.1.8.1 Symptom & UK Rule
The SARS-CoV-2 virus continues to evolve, and two distinct lineages have drawn the attention of health authorities in 2025 and 2026: NB.1.8.1, which prompted a vaccination call in the UK in mid-2025, and BA.3.2, nicknamed “Cicada” by researchers, which has been tracked globally. While neither variant has been shown to cause more severe illness, they have renewed focus on symptoms, immunity, and official guidance.
The UK Health Security Agency (UKHSA) stated in September 2025 that BA.3.2 was increasing in the UK, but there was no evidence it caused more severe disease than other circulating variants. The World Health Organization designated BA.3.2 as a Variant Under Monitoring (VUM) in December 2025, with a risk assessment categorizing the overall public health risk as low. This article summarises what is known about these strains, the symptoms reported, and the current public health approach in the UK.
New Strain of COVID Symptoms
New Variants
Two key strains: NB.1.8.1 (2025, UK) and BA.3.2 / “Cicada” (2026, globally tracked)
Key Symptoms
High temperature, fatigue, sore throat, loss of taste or smell. Cicada may be linked to gastrointestinal issues, but reports of “weird” neurological symptoms are not clinically confirmed.
Current UK Situation
NB.1.8.1 circulating since June 2025; BA.3.2 detected and increasing. UKHSA monitoring both.
Isolation Rules
No legal mandate to isolate. Guidance advises staying home if symptomatic and avoiding contact with vulnerable people.
Key Insights on the Latest Variants
- Two distinct new strains have emerged: NB.1.8.1 (detected June 2025 in the UK) and Cicada (BA.3.2, designated a VUM in December 2025), each with different genetic markers.
- Symptoms for both variants largely mirror Omicron, including cough, fatigue, sore throat, and congestion. No unique symptom profile has been authoritatively tied to BA.3.2 or NB.1.8.1.
- UK isolation rules are based on symptom-driven caution. There is no legal requirement to isolate, but public health advice urges avoiding vulnerable people if unwell.
- Vaccination, including booster doses, remains the primary protection against severe disease from these variants.
- There is high uncertainty about whether Cicada will become dominant globally or cause a significant new wave.
Snapshot: NB.1.8.1 vs. BA.3.2 (Cicada)
| Variant | Year Detected | Key Symptoms (Reported) | Severity | Vaccination Status |
|---|---|---|---|---|
| NB.1.8.1 | 2025 | High temperature, cough, sore throat, loss of taste or smell | Similar to Omicron; severe disease risk low in vaccinated individuals | Current vaccines effective against severe disease |
| BA.3.2 “Cicada” | 2026 (VUM designation Dec 2025) | Fatigue, headache, gastrointestinal upset; “weird” neurological sensations not clinically confirmed | Under investigation; appears less severe than Delta but more transmissible; WHO risk assessed as low | Booster recommended; updated formulations being evaluated |
New Strain of Covid UK
The UK has been monitoring both NB.1.8.1 and BA.3.2. UKHSA said early indicators in September 2025 suggested BA.3.2 and related lineages were increasing in the UK, but current data did not indicate they were more severe than other variants in circulation. This assessment aligns with information from the UKHSA blog – Should we be worried about the current COVID-19 variants?
In June 2025, NHS England issued a call for vaccinations, specifically referencing the NB.1.8.1 variant circulating in the UK. The UK’s approach has focused on vaccination rather than mandates, reflecting a transition to endemic management of the virus.
UKHSA stated in September 2025 that while BA.3.2 was increasing, there was no evidence it caused more severe illness than other circulating variants. Both Dutch surveillance and the World Health Organization have echoed this assessment.
New Strain of COVID Cicada
The variant known as Cicada is the heavily mutated Omicron sublineage BA.3.2, first identified in South Africa in late 2024. It was later detected in multiple countries, including England and the United States. The name “Cicada” was given by researchers, referencing the variant’s pattern of seemingly disappearing and reappearing.
Where Has BA.3.2 Been Detected?
A CDC MMWR report noted that by late 2025, BA.3.2 had been reported by at least 23 countries. Dutch surveillance found the variant in the Netherlands since summer 2025, with its share increasing from week 46 of that year. The first U.S. detections occurred in late 2025, involving two hospitalized older adults with comorbidities and one young child who was treated as an outpatient; all patients survived.
What About Immune Escape?
A key characteristic of BA.3.2 identified by the CDC is its enhanced in vitro immune escape, meaning it can reduce neutralization by antibodies from prior vaccination or infection. However, researchers note that lab escape does not automatically translate to worse illness in the real world. A research review in PMC noted that BA.3.2.2 showed reduced ACE2 binding and lung cell entry, which may constrain its ability to cause rapid dominance.
BA.3.2 may evade immunity more than other variants in lab neutralization studies, but this does not mean it causes more severe illness. UKHSA, WHO, and Dutch authorities all report no evidence of increased severity or hospitalisation for BA.3.2 compared to other Omicron subvariants.
New COVID Isolation Rules
The UK no longer has a legal requirement to isolate after testing positive for COVID-19. The current guidance from UKHSA, updated in September 2025, is based on symptom-driven caution. If you have symptoms of a respiratory infection, such as COVID-19, and you have a high temperature or do not feel well enough to carry out normal activities, you should avoid contact with vulnerable people and stay at home if possible.
If you cannot stay home, UKHSA advises wearing a well-fitting face covering, avoiding crowded places, exercising outdoors where possible, and covering coughs and sneezes while washing hands frequently. This “Living with COVID” guidance remains unchanged and applies across all variants.
Timeline of Key Events
- Late 2024: BA.3.2 (“Cicada”) first identified in South Africa.
- June 2025: UKHSA confirms NB.1.8.1 variant circulating in the UK; NHS England issues a vaccination call.
- Summer 2025: Dutch surveillance detects BA.3.2 in the Netherlands.
- September 2025: UKHSA publishes an update on BA.3.2, stating it is increasing but with no evidence of increased severity.
- December 2025: WHO designates BA.3.2 as a Variant Under Monitoring (VUM) and assesses the public health risk as low.
- Late 2025: CDC MMWR reports first U.S. detections of BA.3.2 in two older adults and one child, all surviving.
- April 2026: ECDC updates its list of variants of concern, including BA.3.2.
What Is Known and What Remains Unclear
| Established Information | Information That Remains Unclear |
|---|---|
| NB.1.8.1 and BA.3.2 are distinct Omicron sublineages with genetic markers. | Whether BA.3.2 will cause a significant new wave or replace existing variants. |
| Reported symptoms are consistent with typical COVID-19 respiratory infection (cough, fatigue, sore throat, headache). | The full range of symptoms for BA.3.2 – reports of “weird” neurological or gastrointestinal symptoms are anecdotal and not clinically confirmed. |
| Current vaccines reduce the risk of severe illness. | Effectiveness of existing vaccine formulations specifically against BA.3.2 transmission. |
| No evidence of increased severity, hospitalisation, or mortality for BA.3.2. | Specific isolation rules differ by country; UK guidance may change in the future. |
Why Two New Variants Appeared in a Single Year
The emergence of two new variants within a year underscores the continuing evolution of SARS-CoV-2. While public attention has waned, health authorities remain vigilant. The Cicada variant’s pattern of disappearing and reappearing introduces uncertainty about seasonal waves. The UK’s response has focused on vaccination rather than mandates, reflecting a transition to endemic management.
For the public, the key takeaway is awareness of evolving symptoms and adherence to vaccination schedules. The CDC MMWR – First Reports of BA.3.2 in the United States noted reduced ACE2 binding and lung cell entry for BA.3.2.2, which may constrain rapid dominance but does not eliminate the possibility of further spread.
What Health Authorities and Researchers Have Said
“The new variant, NB.1.8.1, has been detected in the UK and international data suggests it is more transmissible.”
— UK Health Security Agency (via NHS England)
“The BA.3.2 strain is a mutation of the Omicron variant (BA.1), named Cicada since like the insects, the variant has a pattern of disappearing and reappearing.”
— NewYork-Presbyterian Hospital
Summary: What You Need to Know About the New Strains
Two new COVID variants, NB.1.8.1 and BA.3.2 (“Cicada”), have been detected and are being monitored globally. While BA.3.2 shows enhanced immune escape in lab studies, health authorities in the UK, US, and Europe have found no evidence it causes more severe illness. Symptoms remain those of a typical respiratory infection. The UK recommends symptom-based caution rather than mandatory isolation. Vaccination remains the primary protection against severe disease. More information can be found on the UKHSA blog – Should we be worried about the current COVID-19 variants?
Frequently Asked Questions
Is there a new strain of COVID symptoms?
Yes, two new strains (NB.1.8.1 and BA.3.2 “Cicada”) have been detected. Symptoms generally include high temperature, cough, and fatigue, with Cicada also linked to gastrointestinal issues and unusual neurological sensations, though these are not clinically confirmed.
What are the 2026 COVID variant symptoms?
The 2026 Cicada variant (BA.3.2) symptoms reported include fatigue, headache, nausea, vomiting, and loss of taste or smell. Some reports mention “weird” symptoms like tingling or dizziness, but these are not yet clinically confirmed by health authorities.
Are the “Cicada” and “NB.1.8.1” variants the same?
No. NB.1.8.1 and BA.3.2 (“Cicada”) are distinct variant lineages tracked by the WHO. They should not be combined as one variant. NB.1.8.1 was detected in the UK in June 2025, while BA.3.2 was first identified in late 2024.
Do I need to isolate if I have the new COVID variant in the UK?
No. The UK does not have a legal isolation requirement. Current guidance advises staying at home and avoiding contact with vulnerable people if you have symptoms of a respiratory infection and do not feel well enough to carry out normal activities.
Are current COVID vaccines effective against BA.3.2?
Current vaccines are expected to reduce the risk of severe disease from BA.3.2. However, the variant has shown enhanced in vitro immune escape, meaning it can reduce neutralization by antibodies. Booster doses are recommended.
What countries has BA.3.2 been detected in?
A CDC MMWR report noted BA.3.2 had been reported by at least 23 countries as of late 2025, including the United States, England, the Netherlands, and South Africa.
Has BA.3.2 caused any deaths?
The CDC report on the first U.S. cases noted all patients survived, including two hospitalized older adults with comorbidities and one young child. No evidence of increased mortality for BA.3.2 has been reported.
Is BA.3.2 more severe than other variants?
No. The WHO assessed the public health risk as low, and UKHSA and Dutch authorities have stated there is no evidence BA.3.2 causes more severe illness than other circulating Omicron subvariants.
Will I need another booster for the new strain?
Health authorities recommend staying up to date with COVID-19 vaccinations, including booster doses, as they remain the primary protection against severe disease. Updated formulations are being evaluated.
Where can I find official updates on COVID variants?
Official updates are published by the UK Health Security Agency, the World Health Organization (WHO variant dashboard), the European Centre for Disease Prevention and Control, and the US Centers for Disease Control and Prevention.
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